- Patients having serious, unstable or terminal medical or neurologic illness that would compromise study participation (i.e., metastatic or advanced malignancy, chronic renal failure requiring dialysis, recent myocardial infarction or unstable angina, or "end stage" chronic obstructive pulmonary disease). People with common conditions such as hypertension, insulin dependent diabetes mellitus, asthma, compensated congestive heart failure, a malignancy in remission, treated hypothyroidism, or epilepsy will not be excluded from participation.